Greetings, all. A program failure has made me look at the definition of the rename() function. I find that the IBM run-time library reference (iSeries ILE C/C++ for iSeries Run-Time Library Functions, Version 5; SC41-5607-01) says explicitly that the "to" parameter must not name an existing file. The Posix definition <http://www.opengroup.org/onlinepubs/007908799/xsh/rename.html> on the other hand allows this situation and specifies the behaviour of the function in this case. Surely rename() is a commonly used part of Posix. Do I have to do something special to get Posix compatibility? Thank you for your attention. Terry. Available for contract programming.